BACTE MODULE 2

• Spirochetes

  These are diverse group of pathogens that

  infect human and animals.

  • 3 genera (Borrelia, Treponema and

  Leptospira)
• Borrelia

  ➢ A group of arthropod-borne pathogens

  ➢ Transmitted and maintained by ticks

  ➢ Infections possess a blood-borne phase which

  advances into generalized and local infections

  with varying clinical signs.
• Species of Borrelia associated with animal infections

  ➢B. anserina (Fowl spirochaetosis)

  ➢B. theileri (Cattle relapsing fever)

  ➢B. burgdorferi (Lyme disease of dogs,

  horses, cattle)

  ➢B. coriaceae (Epizootic bovine abortion)

  ➢B. canis (Intestinal diseases of dogs)

  ➢B. hyos (Swine pathogen)
• Morphology, staining features and cellular composition of Borrelia

  ▪ Gram-negative but stain well with Giemsa and Wright

  ▪ Spirals with a characteristic motility (Darkfield

  microscopy)

  ▪ Possess axial fibrils which differ across species

  ▪

  ▪ Pathogens possess a linear double-stranded

  chromosome with approximately 900 kbp and multiple

  linear and circular plasmids

  ▪ Genes that express outer surface proteins are in their

  genetic elements.
• Growth characteristics of Borrelia

  ➢ Pathogenic Borrelia (B. anserina) grow well in embryonated

  eggs

  ➢ B. burgdorferi can be cultivated in Modified Kelly’s medium

  (BSK) at 33 oC

  ➢ Borrelia are slow-growing micro-aerophiles

  ➢ They ferment glucose and other carbohydrates

  ➢ These are either anaerobes or facultative anaerobes

  ➢ No report on growth of the organisms in an artificial medium
• Reservoir of Infection (Borrelia)

  ➢ Wounds

  ➢ Placenta

  ➢ Milk

  ➢ Urine

  ➢ Feces
• Transmission of Borrelia

  ➢ Through tick vectors

  ➢ Trans-ovarian (maternal)

  ➢ Cannibalism
• Fowl spirochetosis and Goose Septicemia

  Etiologic agent: B. anserina

  Vector: Argas persicus

  Animals susceptible to infection

  Chicken, turkey, geese, duck, pheasant, pigeons and canaries

  Clinical signs

  Cyanosis and greenish diarrhea, paralysis, anemia

  Postmortem findings

  Splenomegaly and widespread hemorrhages

  Enlargement of the liver

  Semi-fibrinous exudates in the pericardial sac
• Lyme Disease/Borreliosis

  Etiologic agent: B. burgdorferi

  Vectors: Ixodes scapularis, Ixodes pacificus

  Animals susceptible to infection

  Dogs, horses, cattle (abortion), humans

  Clinical signs

  Skin lesions (erythema migrans in humans)

  Cardiac signs

  Arthritis, ocular and neural involvement (horses)

  Lymphadenopathy

  Abortion (cattle)
• Virulence factors of pathogenic Borrelia

  ➢ Muramic acid and ornithine cell wall (B. anserina)

  ➢ Endotoxins

  ➢ Hemolysin (B. burgdorferi)
• Laboratory Diagnosis

  Samples: Liver, blood, synovial fluid, spleen

  Preferred culture media: Chick embryo

  Agent identification (Basic and advanced methods)

  ➢ Demonstration of Borrelia spirals in Giemsa-stained

  blood, splenic and hepatic smears of birds

  ➢ Inoculation of the pathogen in a BSK II medium at

  33oC

  ➢ Darkfield microscopy

  ➢ ELISA

  ➢ PCR using genus specific DNA primers

  ▪
• Treatment with antibiotics of Borrelia

  Penicillin

  Streptomycin

  Tetracycline

  Doxycycline

  Enrofloxacin

  Erythromycin
• Control and prevention of Borrelia

  • Tick or ectoparasite control
• Treponema

  ➢ Organisms are found in the oral cavity, intestinal

  tract and genital regions (humans and animals)

  ➢ These are associated with spirochetal infections of

  pigs which are reportedly immune-compromised.
• Species of Treponema associated with animal infections

  T. hyodysenteriae (Brachyspira hyodysenteriae, Serpulina hyodyenteriae)

  T. suis

  T. intermedius

  T. cuniculi
• Morphology, staining features and cellular composition of Treponema

  ➢ These organisms are loosely coiled (Darkfield microscopy)

  ➢ These are Gram-negative microbes

  ➢ Smears from infected tissues stain well with Romanovsky

  ➢ Treponema possess axial filaments which differ across

  species

  ➢ Treponema possess a 26.9 kDa protein responsible for the

  beta-hemolytic activity of some pathogenic forms
• Growth characteristics of treponema

  ➢ Pathogens are obligate anaerobes

  ➢ They require organic materials if grown in a closed

  environment that makes them grow for long

  periods at temperature of 5 to 25°C
• Reservoir of infection of treponema

  • GI tract of pigs

  • Feces of dogs Transmission

  ➢Feco-oral route
• Rabbit syphilis or vent disease

  Etiologic agent: T. cunicula

  Clinical signs

  Diarrhea

  Postmortem findings

  Ulcers in the genital and perineal areas
• Swine dysentery or bloody Scours

  Etiologic agent: T. hyodysenteriae (Brachyspira

  hyodysenteriae, Serpulina hyodysenteriae)

  ➢ The agent of swine dysentery produces disease in the colon.

  ➢ Microorganism invades the goblet cells of the colon and

  multiplies in the crypts of Lieberkuhn.

  ➢ The condition is accompanied by colonic malabsorption and

  presents with muco-hemorrhagic colitis that results to the

  excretion of feces with mucous and blood.

  Clinical signs

  ➢ Elevated temperature

  ➢ Bloody diarrhea

  ➢ Dehydration; acidosis

  ➢ and hyperkalemia in extreme cases
• T. hyodysenteria (hemorrhagic feces)
• Virulence factors of pathogenic Treponema

  • Lipoproteins

  • Outer envelope proteins
• Laboratory diagnosis of treponema

  Samples: Smears of fecal material, intestinal

  mucosal scrapings

  Preferred culture media: blood agar plates with

  spectinomycin

  Agent Identification (Basic and advanced methods)

  • Phase Contrast Microscopy, Darkfield

  Microscopy

  • PCR using primers for Treponema
• Treatment with antibiotics of Treponema

  ➢ Organic arsenicals

  ➢ Tylosin

  ➢ Gentamycin

  ➢ Nitrofurazone

  ➢ Lincomycin

  Control and prevention

  • Intensified

  management program
• LEPTOSPIRA

  ➢ These pathogens are reported as

  morphologically and physiologically

  uniform but serologically and

  epidemiologically diverse.

  ➢ Leptospirae are often referred to as

  smallest spirochetes.

  ➢ These are thin spiral microorganisms

  found in a variety of moist habitats.
• Species of Leptospira associated with animal infections

  • L. pomona (common in cattle, swine, horse and sheep)

  • L. icterohemorrhagica (rodents as principal hosts while dogs, horses, cattle and swine are clinical hosts)

  • L. bratislava (common in swine, horse and sea lions)
• Morphology of leptospira

  ➢ Gram-negative organisms which are hardly recognizable in routinely fixed smears.

  ➢ These are thin spiral organisms which require darkfield or phase contrast microscopy for visualization.

  ➢ The organisms possess a hook at each end make them S or C-shaped. Wet mounts reportedly reveal them to be motile.

  ➢ Leptospira possess outer sheath and axial fibrils.

  ➢ The outer sheath takes the features of a capsule and outer membrane.

  ➢ It contains endotoxin in its cell wall while a hemolysin (sphingomyelinase C) is associated with some serovars.
• Growth characteristics of leptospira

  ➢The organisms grow aerobically at 30οC.

  ➢Growth is enhanced by the supplementation of 10% rabbit

  serum (Fletcher’s medium/Stuart broth) in solutions of saline

  and peptone, vitamins, electrolytes and buffers with no

  protein.

  ➢They produce little turbidity in a fluid medium while growth

  may be concentrated in a disc (dinger zone) below the

  surface of a semisolid medium.
• Reservoir of infection of Leptospira

  ➢ Mammalian kidneys

  ➢ Birds, reptiles, amphibians and invertebrates

  ➢ Rodents and wild carnivores (carriers)
• Transmission of leptospira

  ➢ Ingestion of milk from infected cows

  ➢ Genital excretions from cattle and swine

  ➢ Contact of mucus membranes and skin with urine

  contaminated water, fomites and feed
• Canine leptospirosis

  Etiologic agents: L. icterohemorrhagia and L. canicola

  Clinical signs

  ➢ Hemorrhages on the skin and mucus membranes, epistaxis and blood-stained vomitus and feces
• Course of canine leptospirosis

  ➢ Septicemic, hepatic and renal disease in 1 to 3-year old dogs

  ➢ Pathogen enters bloodstream after infection of mucus membranes and reproduce

  ➢ Liver and kidneys are colonized and produce degenerative changes and injury of renal tubules

  ➢ Renal localization of the pathogen causes nitrogen retention, renal casts and leukocytes appear in the urine

  ➢ Muscles, eyes, meninges are damaged

  ➢ Destruction of vascular epithelium and RBC destruction
• Types of canine leptospirosis

  1. Icteric type (has a slower course, marked by prominent icterus)

  2. Uremic type (Destruction is directed on the kidneys,

  accompanied by gastrointestinal upsets uremic breath and

  ulcerations in the anterior alimentary tract)
• Equine Leptospirosis

  Etiologic agents: L.pomona, L. grippotyphosa,

  L. icterohemorrhagiae

  ➢ This is marked by fever, mild icterus and abortion

  ➢ With inflammation of the eyes (Uveitis), recurrent

  iridocyclitis or periodic ophthalmia (moon blindness

  or periodic opthalmia)
• Swine Leptospirosis

  Etiologic agents: L. pomona, L. icterohemorrhagiae, L.

  canicola, L. muenchen, L. tarassovi, L. bratislava

  ➢ This is marked by abortion and infertility in sows

  ➢ Septicemia with icterus in piglets

  ➢ Abortion, stillbirth and infertility (sows)
• Bovine Leptospirosis

  Etiologic agents: L. pomona and L. hardjo

  ➢ This is marked by abortion (late term) in adults due to

  fetal death

  ➢ Fetal retention with autolysis

  ➢ Weak calf syndrome and a marked milk drop syndrome

  and reproductive failure and infertility

  ➢ Fever, hemoglobinuria, icterus and anaemia
• Leptospirosis in Sheep and Goats

  Etiologic agents: L. pomona, L. hardjo, L .grippotyphosa

  ➢ Anaemia, jaundice, dyspnea
• Virulence Factors of Leptospira

  ➢ Cold hemagglutinin (induces auto-immune lysis of

  erythrocytes)

  ➢ Cytotoxin (damages endothelial cells)

  ➢ Urease (damages urinary epithelium)

  ➢ Hemolytic exotoxin (responsible for hemoglobinuria)

  ➢ Agalactia-associated toxin
• Laboratory diagnosis of leptospira

  Samples: Blood, urine, cerebro-spinal fluid, uterine fluid and

  placental cotyledons, aborted fetuses, samples of

  the kidney, liver, spleen, brain, eyes

  Preferred culture media: Oxalated human blood, Fletcher’s

  medium, Ellinghausen medium, McCullough

  medium, Johnson and Harris (EMJH medium)

  Agent identification

  ➢Visual examination of wet mounts

  ➢PCR that applies specific primers for leptospira DNA

  ➢Darkfield and phase contrast microscopy (urine

  samples)

  ➢Animal inoculation (hamsters and guinea pigs)

  ➢Serological testing
• Treatment with antibiotics of leptospira

  ➢ Penicillin

  ➢ Tetracycline

  ➢ Streptomycin

  ➢ Fluoro-quinolones

  Control and prevention

  ➢ Vaccination of animals

  ➢ Sanitation and hygiene